#include <iostream>
using namespace std;

int main()
{
	string s1 = "hellow world";
	string s2(s1);
	string s3 = s1;
	string& s4 = s1;
	string s5(s2, 1, 6);
	string s6(s2, 1);
	string s7(s2, 1, 100);
	string s8(s2, 5);
	cout << s1 << endl;
	cout << s2 << endl;
	cout << s3 << endl;
	cout << s4 << endl;
	cout << s5 << endl;
	cout << s6 << endl;
	cout << s7 << endl;
	cout << s8 << endl;
	return 0;
}